Many downhole operations require sequential dropping of various objects downhole to facilitate a downhole operation. The sequence may involve dropping a ball on a ball seat to close off the wellbore to allow pressure to be built up to actuate tools such as packers or hangers or downhole valves. Cementing operations typically involve dropping one or more wiper plugs in a specific order to, for example, wipe the wellbore clean of the cement. These objects to be dropped downhole are frequently assembled in surface equipment referred to as a plug-dropping head. In the past, plug-dropping heads have been stacked vertically to accommodate the sequential dropping of objects downhole. Thus, the lowermost object would be dropped first and so forth up until the topmost plug-dropping head has released the object stored therein. The problem with this arrangement is that it gets to be quite tall and in most applications, the plug-dropping heads are inaccessible. One way the prior designs have compensated for this inaccessibility problem is to actuate the plug-dropping heads by remote control. Such techniques are described in U.S. Pat. Nos. 5,435,390 and 5,590,713.
One of the objects of the present invention is to provide a compact design which can be operable to insert a plurality of objects downhole within fairly confined vertical space limits at the surface. The object of the device is to present a compact design which can efficiently deliver a series of objects downhole. Another object of the invention is to allow circulation to continue as the device operates to sequentially drop objects downhole. These and other advantages of the present invention will become more apparent to those skilled in the art from a review of the description of the preferred embodiment below.